The monkey at last became angry because__________.
A.the old man didn't give his monkey everything
B.the old man made the money do everything
C.the old man often fell asleep during the day
D.he couldn't drive the fly away
D、he couldn't drive the fly away
解析:解析:从文章第二段:This continued about four or five times.The monkey at last became very angry.得知。故本题答案为D。